GridView4.AllowSorting = true;
　　　　　　　　　　　　GridView4.Attributes.Add("SortExpression", "ENDDATE");                    GridView4.Attributes.Add("SortDirection", "ASC");

    /// <summary>    /// GridView4的排序    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    protected void GridView4_Sorting(object sender, GridViewSortEventArgs e)    {        // 从事件参数获取排序数据列        string sortExpression = e.SortExpression.ToString();        // 假定为排序方向为“顺序”        string sortDirection = "ASC";        // “ASC”与事件参数获取到的排序方向进行比较，进行GridView排序方向参数的修改        if (sortExpression == this.GridView4.Attributes["SortExpression"])        {            //获得下一次的排序状态            sortDirection = (this.GridView4.Attributes["SortDirection"].ToString() == sortDirection ? "DESC" : "ASC");        }        // 重新设定GridView排序数据列及排序方向        this.GridView4.Attributes["SortExpression"] = sortExpression;        this.GridView4.Attributes["SortDirection"] = sortDirection;　　　　 //获取展示数据
        DataTable table = SocketInfo.GetStatusInfo(sortExpression, sortDirection);        GridView4.DataSource = table;        GridView4.DataBind();        GridView4.Visible = true;    }